Automated glass capillary gas chromatographic analysis of PCB and organochlorine pesticide residues in agricultural products

Complicated PCB mixtures can be separated in individual compounds using glass capillary gas chromatography, (GC)². Depending on extraction and clean-up procedure it is also possible to separate and determine organochlorine pesticides at the same time. This (GC)² technique can be used to determine the contents of individual chlorinated biphenyls in milk products and animal feedstuffs and in the analysis of complicated extracts of soil and vegetable material. Practical aspects concerning connection of the capillary, automatic splitless injection, repeatability of the retention time, quality of the column with respect to separation and adsorption and degradation of DDT are discussed. The detection of individual chlorinated biphenyls is possible at the ppb level in fats and vegetable materials, using an extraction and clean-up procedure, based on saponification of the sample. Preliminary results for milk, obtained from several areas, are shown.     

Separation of (3R, 3′ R)-, (3R, 3′ S; meso)-, (3S, 3′ S)- Zeaxanthin, (3R, 3′ R, 6′ R)-, (3R, 3′ S, 6′ S)- and (3S, 3′ S, 6′ S)-Lutein via the dicarbamates of (S)-(+)-α-(1-naphthyl) ethyl isocyanate

A method is described for the qualitative and quantitative determination of configurational isomers of zeaxanthin (=3,3′ -dihydroxy-β, β -carotene) and lutein (=3,3′ -dihydroxy-α -cartotene). It is based on the reaction of these zeaxathin and lutein isomers with (S)-(+)-α-(1-naphthyl) ethyl isocyanate to afford diastereomeric dicarbamates, which are analyzed by HPLC.     

Solution extraction of transition and post-transition heavy and precious metals by chelate and macrocyclic ligands

This review focuses on compounds and methods that can be used for the extraction and separation from solution of two classes of elements that we define as heavy metals and precious metals. These elements are often targeted because they are toxic, costly, and their coordination chemistry has already been well studied, and because there is a need to develop methods of economically extracting, separating and recovering them from waste sites. This review outlines possible strategies that can be used, and reviews the present literature regarding the available methods for their extraction.     

Separation of trace amounts of titanium by the sorption of the titanium peroxocomplex on silica gel

Summary The possibility of the analytical use of the sorption of titanium peroxocomplex on silica gel for the determination of trace amounts of titanium was studied. The exchange capacity of silica gel in dependence on the time and the composition of the titanium peroxocomplex sorbed were described. A simple and very efficient separation procedure has been developed for the determination of traces of titanium in various waters and water-soluble salts.     

The measurement of dynamic surface tension by the maximum bubble pressure method

The principle of maximum pressure in a bubble for measurements of dynamic surface tension is realized in a fully automatically operating apparatus. The set-up yields data in the time interval from 1 ms up to several seconds and can be temperature controlled from 5° to 80°C. Experimental data obtained for different surfactants and gelatine in water and/or water/glycerine mixtures at different temperatures are discussed. A direct comparison with results from oscillating jet and inclined plate experiments shows excellent agreement.     

用全氟表面活性剂改善Nafion膜表面的亲水性

在Ｎａｆｉｏｎ膜表层引入全氟表面活性剂可改善膜表面的亲水性，其中全氟磺酸表面活性剂ＦＣ－９９效果好，经后者处理的Ｎａｆｉｏｎ膜几乎不溶胀，而能使水溶液在膜上的接触角显著减小，并改善“气泡效应（零间距效应）”。     

Poly(vinylpyrrolidone)-coated silica: A versatile,polar stationary phase for HPLC

Summary Poly(vinylpyrrolidone) (PVP) is immobilized on both, small- and large-pore silicas by thermal treatment, γ-radiation, or peroxide initiated polymerization. The hydrolytic stability of such a highly polar stationary phase significantly exceeds that of a comparable phase prepared by the chemical reaction of silica with a pyrrolidone ethyl dimethylchlorosilane silanization reagent. The properties of the different PVP-silicas are evaluated by elemental analysis, spectroscopy, and chromatography. Columns of PVP-silica packings can be used in several modes: a) under normal-phase conditions as a polar bonded stationary phase, b) under reversed-phase conditions, for the separation of organic proton-donor and hydrogen-bonding compounds, c) for the aqueous size exclusion chromatography of proteins, and d) with salt gradients for the hydrophobic interaction chromatography of proteins. The minimum observable reduced plate-height of PVP-silica columns is about 3. Double-layer polymer coating experiments using PVP-silica covered with poly(methyloctadecylsiloxane) have been performed to study diffusion and shielding effects of different polymer layers in the stationary phase. Depending on separation conditions, one or the other polymer governs the retention process. A mixed selectivity was observed in a reversed phase mode with acidic eluents.     

Nonlinear fluctuations,separation of procedures,and linearization of processes

A concept of separation of procedures is introduced to study cooperative phenomena theoretically. Some typical important examples of this concept are presented to clarify its usefulness; Kubo's stochastic Liouville equation, some generalized diffusionlike equations, van Kampen's expansion, Kubo's extensivity, Prigogine's entropy production, the scaling theory of transient phenomena based on the Lie algebra, and Suzuki's CAM theory of cooperative phenomena are discussed from the new viewpoint of separation of procedures.This paper is dedicated to Ilya Prigogine on the occasion of his 70th birthday.     

α-蒎烯水合主产物的分离与提纯

根据α-蒎烯水合产物中的龙脑、异龙脑和α-松油醇在邻苯二甲酸酐存在下发生酯化、脱水反应的选择性差异，可将三者大部分分离，提高优质龙脑和α-松油醇的得率。．     

Theoretical studies of mercury intrusion in some networks: Testing the applicability of mercury intrusion in the size characterisation of the lacunar pore space of soil samples

At the textural level, it is possible to consider the organization of soil components as a characteristic feature of those materials. This organization confers a pore space specific to the clay phase and a lacunar pore space which is present between clay masses. The lacunar pore space may be regarded as a generally continuous network, whose dimensions are much larger than those of the clay pore space.Mercury porosimetry is a technique for characterizing the size of this pore space. Nevertheless, the obtained data cannot be used directly for various reasons related to pore shape and arrangement. Therefore, a study was conducted to better determine limitations of the available data. This study is based on mercury intrusion simulations in fictitious capillary and bubble networks.The conclusion is that it is impossible to obtain the actual pore size distribution of soil lacunar pore space. The data permit us to define only a value connected with a threshold. This threshold is related to the mean value of bonds per node and to the distribution of bond constrictions. So, it seems that any use of the mercury porosimetric data to characterize the soil lacunar pore space has to be careful.